There are still neighbors that keep annoying you by having loud the TV or the radio? Well I have you the solution. In fact all neighborhood will face your jamming waves at their TVs and radios, so be careful. This Jammer is the improved version of the old "TV and FM jammer schematic" with the difference of much higher power. Many of you where asking for a stronger and wider effect but to be as portable as can be. Looking at the schematic you can see that, only the.....
This transmitter can be used for transmitter hunts, for remote key finding, or for radio telemetry in model rockets. It can be tuned to the two meter band or other VHF bands by charging Cl and Ll. 11 is four turns of #20 enameled wire airwound, 0.25 inch in diameter (use a drill bit), 0.2 inch long, centertapped. The antenna can be 18 inches of any type of wire. IC2 functions as an audio oscillator that is turned on and off by IC1 about once per second. ..
The AA-7 active antenna contains only two active elements: Ql (an MFE201 N-chanriel dual-gate FET) and Q2 (a 2SC2570 ripri VHF silicon transistor), which provide the basis of two independent,..
A 30- to 50-cm whip antenna provides reception from 10 kHz to over 220 MHz. Tl, a dual-gate MOSFET, provides low noise, high-input impedance, and high gain,..
The CD4069 or 74C04 hex inverter—is used as^ fixed-frequency oscillator centered around 100 kHz. U2 contains the variable frequency oscillator and balanced modulator. The CD4046 is a phase-locked loop and R3, R4, and C2 determine the center frequency of the on-chip oscillator. The antenna forms a parallel capacitance with C2, which allows the frequency to be shifted several kilohertz by bringing a hand near the antenna. R4, the ZERO control, allows the variable.....
To display an rf signal, connect LI to the transmitter and points A and B to the vertical plates of the oscilloscope. Adjust LI for minimum SWR and C3 for the desired trace height on the CRT..
This field-strength meter is useful for antenna testing. It covers 6 to 60 MHz and uses a rugged 0-to-l mA meter. A 9..
This wideband antenna preamplifier has a gain of around 20 dB from 40 to 860 MHz, covering the entire VHF, FM, commercial, and UHF bands...
This locater is made up of two parts. The first is an rf oscillator, whose circuit is shown in Fig. 8-4a. The second is a sensitive receiver shown in Fig. 8-4b. The heart of the oscillator is a 555 timer !C. Tank circuit C2 and L1 is used to tune the transmitter. The antenna is coupled to the transmitter through C3. A telescopic antenna or a length of hookup wire will work quite well. At the receiver, the incoming signal is tuned by C5 and L2 before being passed on to.....
The heart of the electroscope is the two junction FETs Ql and Q2 connected in a balanced-bridge circuit. The gate input of Ql is connected to the wire pick-up antenna, while Q2"s gate is tied to the circuit"s common ground through R2. That type of bridge circuit offers excellent temperature stability; therefore, Ql is allowed to operate in an open-gate configuration. ..
An inexpensive. antenna-mounted, UHF-TV preamplifier can add more than 25 dB of gain. The first stage of the preamp is biased for optimum noise, the second stage for optimum gain. ..
The schematic shown, is a 2 transistor signal amplifier between 10 MHz to 30 MHz. The BF256C and the BF494 are very popular transistors and are easy to find. The transformer works as insulator and amplifier. http://www.next.gr/rf/antennas/active-antennas/..
C1 = 3 750 pF 500 V silver-mica capacitor. C2= 100 pF preset capacitor (Jackson C803). C3 = 75 pF variable capacit..
This circuit is useful in amateur radio VHF and UHF work where a mast-mounted antenna preamp is used for receiving. The kit controls T-R switching and change-over relay sequencing so that high RF levels are prevented ..
Using only one IC and six passive components, this pulse generator has a frequency range of 400 to 4000 Hz and an adjustable duty cycle of 1 to 99%. A threshold detector (ICA) and an integrator (ICB) generate a triangular waveform. A positive voltage at the output of ICA causes the output of ICB to become a negative-going ramp. When the output of this ramp reaches a certain value, ICA, by virtue of its positive-feedback network, changes state; its output becomes negative,.....
This small circuit is a Linear amplifier for driving small UHF TV transmitters. Its gain is 7dB and can amplify a signal between 450-800 MHz. You can drive the circuit with 1 to 1,5 Watts signal. Better use double layer PCB with the second layer connected to earth. Use a stabilized power supply 25 volts and at least 5Amps...
Positive output step-up and step-down de-de converters have a common limitation in that neither can handle input voltages that are both greater than or less than the output. For example, when converting a 12-V sealed lead/acid battery to a regulated +12 V output, the battery voltage might vary from a high of 15 V down to 10 V. By using a MAX641 to drive separate P-and N-cbannel MOSFETs, both ends of the inductor are switched to allow noninverting buck/boost operation. ..
The use of a loop antenna of large size (12 18") provides a large signal pickup at AM broadcast frequencies. It has..
The range of this transmitter is about 50 feet with a short whip antenna. The tone generator, is made up of a unijunction transistor, Q1, and R1, R2, R3, and C2. Transistor Q1 pulses on and off at a rate determined by the time constant of R1 and R2, together with the capacitance of C2 and the B1-emitter junction of QL Trimmer potentiometer R2 determines the frequency of the tone generated and allows a range of approximately 100 Hz to over 5 kHz. ..
This circuit is configured for the 80m band. The 365-pF, broadcast-band variable capacitor should have a vernier drive with a six-to-one ratio, which makes tuning easier by separating the stations on the dial. A good antenna and ground are also recommended. ..
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